Neuron specific stc mRNAs, expressed in human brain tissue by alternative splicing, are related to neural differentiation. The ability of neuroblastoma to mature colud be associated with neuronal c-srcN1 expression, and c-srcN2 mRNA is induced in chemically differentiated neuroblastoma cells in vitro. The prognosis of patient with neuroblastoma is strongly affected by the ability of the tumor to differentiate in vivo. Toward clarification of the relationship between neuronal src mRNAexpression and clinical feature of neutoglastoma, we analyzed 28 human neuroblastoma tissues for expression of src mRNAs by S1 nuclease protection assay, N-myc gene amplification was also examived by Southern blot hybridization and the clinical significance of neuronal src mRNA and its relevance to N-myc gene amplification were inbestigated. Expression of c-srcN2 mRNA at high ratio (more than 10 %)were at advanced stage and had aggressive phenotype in clinical course. Genomic amplification of N-myc gene and expression of c-srcN2 mRNA were correlated inversely. Expression of c-srcN2 mRNA could be a new biological marker to predict the prognosis of patients with neuroblastoma when combined with other prognostic marker such as N-myc gene amplification.